Method and apparatus to treat conditions of the naso-pharyngeal area

ABSTRACT

A patient&#39;s upper airway condition such as snoring and sleep apnea is treated by selecting a particulate material selected for limited migration within tissue and for encouraging a fibrotic response of tissue to the material. A bolus of the particulate material is injected into the tissue area to structurally stiffen the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of application Ser. No.10/629,145, filed Jul. 29, 2003, now U.S. Pat. No. 6,971,396 which is acontinuation of application Ser. No. 10/394,887, filed Mar. 21, 2003,now U.S. Pat. No. 6,742,524 which is a continuation of application Ser.No. 10/190,183, filed Jul. 3, 2002, now U.S. Pat. No. 6,546,936, whichis a continuation of application Ser. No. 09/636,803, filed Aug. 10,2000, now U.S. Pat. No. 6,431,174, which applications are incorporatedherein by reference.

BACKGROUND

1. Field of the Invention

This invention is directed to methods and apparatuses for treatingconditions of the naso-pharyngeal area such as snoring and sleep apnea.More particularly, this invention pertains to method and apparatus tostiffen tissue of the naso-pharyngeal area.

2. Description of the Prior Art

Snoring has received increased scientific and academic attention. Onepublication estimates that up to 20% of the adult population snoreshabitually. Huang, et al., “Biomechanics of Snoring”, Endeavour, p.96–100, Vol. 19, No. 3 (1995). Snoring can be a serious cause of maritaldiscord. In addition, snoring can present a serious health risk to thesnorer. In 10% of habitual snorers, collapse of the airway during sleepcan lead to obstructive sleep apnea syndrome. Id.

Notwithstanding numerous efforts to address snoring, effective treatmentof snoring has been elusive. Such treatment may include mouth guards orother appliances worn by the snorer during sleep. However, patients findsuch appliances uncomfortable and frequently discontinue use (presumablyadding to marital stress).

Electrical stimulation of the soft palate has been suggested to treatsnoring and obstructive sleep apnea. See, e.g., Schwartz, et al.,“Effects of electrical stimulation to the soft palate on snoring andobstructive sleep apnea”, J. Prosthetic Dentistry, pp. 273–281 (1996).Devices to apply such stimulation are described in U.S. Pat. Nos.5,284,161 and 5,792,067. Such devices are appliances requiring patientadherence to a regimen of use as well as subjecting the patient todiscomfort during sleep. Electrical stimulation to treat sleep apnea isdiscussed in Wiltfang, et al., “First results on daytime submandibularelectrostimulation of suprahyoidal muscles to prevent night-timehypopharyngeal collapse in obstructive sleep apnea syndrome”,International Journal of Oral & Maxillofacial Surgery, pp. 21–25 (1999).

Surgical treatments have been employed. One such treatment isuvulopalatopharyngoplasty. In this procedure, so-called laser ablationis used to remove about 2 cm of the trailing edge of the soft palatethereby reducing the soft palate's ability to flutter between the tongueand the pharyngeal wall of the throat. The procedure is frequentlyeffective to abate snoring but is painful and frequently results inundesirable side effects. Namely, removal of the soft palate trailingedge comprises the soft palate's ability to seal off nasal passagesduring swallowing and speech. In an estimated 25% ofuvulopalatopharyngoplasty patients, fluid escapes from the mouth intothe nose while drinking. Huang, et al., supra at 99.Uvulopalatopharyngoplasty (UPPP) is also described in Harries, et al.,“The Surgical treatment of snoring”, Journal of Laryngology and Otology,pp. 1105–1106 (1996) which describes removal of up to 1.5 cm of the softpalate. Assessment of snoring treatment is discussed in Cole, et al.,“Snoring: A review and a Reassessment”, Journal of Otolaryngology, pp.303–306 (1995).

Huang, et al., supra, describe the soft palate and palatal snoring as anoscillating system which responds to airflow over the soft palate.Resulting flutter of the soft palate (rapidly opening and closing airpassages) is a dynamic response generating sounds associated withsnoring. Huang, et al., propose an alternative touvulopalatopharyngoplasty. The proposal includes using a surgical laserto create scar tissue on the surface of the soft palate. The scar is toreduce flexibility of the soft palate to reduce palatal flutter. Huang,et al., report initial results of complete or near-complete reduction insnoring and reduced side effects.

Surgical procedures such as uvulopalatopharyngoplasty and those proposedby Huang, et al., continue to have problems. The area of surgicaltreatment (i.e., removal of palatal tissue or scarring of palataltissue) may be more than is necessary to treat the patient's condition.Surgical lasers are expensive. The proposed procedures are painful withdrawn out and uncomfortable healing periods. The procedures havecomplications and side effects and variable efficacy (e.g., Huang, etal., report promising results in 75% of patients suggesting a fullquarter of patients are not effectively treated after painful surgery).The procedures may involve lasting discomfort. For example, scar tissueon the soft palate may present a continuing irritant to the patient.Importantly, the procedures are not reversible in the event they happento induce adverse side effects not justified by the benefits of thesurgery.

In pharyngeal snoring, the pharyngeal airway collapses in an areabetween the soft palate and the larynx. One technique for treatingairway collapse is continuous positive airway pressure (CPAP). In CPAPair is passed under pressure to maintain a patent airway. However, suchequipment is bulky, expensive and generally restricted to patients withobstructive sleep apnea severe enough to threaten general health. Huang,et al. at p. 97.

A technique for snoring treatment is disclosed in commonly assigned andcopending U.S. patent application Ser. No. 09/513,432 filed Feb. 25,2000. According to certain embodiments of that application, permanentimplants are placed in the soft palate to add stiffness to the softpalate.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, methods andapparatuses are disclosed for treating a patient's upper airwaycondition such as snoring and sleep apnea. The invention includesselecting a particulate material selected for limited migration withintissue and for encouraging a fibrotic response of tissue to thematerial. A bolus of the particulate material is injected into thetissue area to structurally stiffen the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows, in cross-section, a naso-pharyngeal area of an untreatedpatient;

FIG. 2 shows a soft palate viewed through an open mouth of the untreatedpatient of FIG. 1;

FIG. 3 is a front view of an interior of the mouth shown in FIG. 1 andshowing an area to be ablated according to a first prior art surgicalprocedure;

FIG. 4 is the view of FIG. 3 and showing an area to be scarred accordingto a second prior art surgical procedure;

FIG. 5 is a schematic representation of a spring-mass system model ofthe soft palate;

FIG. 6 is the view of FIG. 1 with the soft palate containing an implantin the form of a unit of mass;

FIG. 7 is the view of FIG. 3 showing the unit of mass of FIG. 6;

FIG. 8 is the view of FIG. 6 with the soft palate containing an implantin the form of a longitudinal member;

FIG. 9 is the view of FIG. 7 showing the implant of FIG. 8;

FIG. 10 is a perspective view of the implant of FIG. 8;

FIG. 11 is a perspective view of a braided implant;

FIG. 12 is a side-sectional view of a delivery system for placing animplant in the soft palate;

FIG. 13 is an exploded view of FIG. 12 following delivery of the implantfrom the delivery system;

FIG. 14 is the view of FIG. 1 with the soft palate containing an implantin the form of a bolus of micro-beads deposited in a linear path;

FIG. 15 is the view of FIG. 3 showing micro-beads deposited as sphericaldeposits; and

FIG. 16 is a schematic representation showing a patch for delivering abolus of micro-beads through a plurality of needles.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A. Physiology Background

Referring now to the several drawing figures, in which identicalelements are numbered identically throughout, a description of apreferred embodiment of the present invention will now be provided.

FIG. 1 shows, in cross-section, a naso-pharyngeal area of an untreatedpatient. FIG. 2 shows a soft palate SP viewed through an open mouth ofthe untreated patient. FIG. 1 shows the nose N, mouth M and throat TH.The tongue T is shown in an oral cavity OC of the mouth. A hard palateHP (containing a bone B) separates the oral cavity OC from the nasalcavity NC. The nasal concha C (soft tissue which defines, in part, thenasal sinus—not shown) resides in the nasal cavity NC.

The soft palate SP (a muscle activated soft tissue not supported bybone) depends in cantilevered manner at a leading end LE from the hardpalate HP and terminates at a trailing end TE. Below the soft palate SP,the pharyngeal wall PW defines the throat passage TP. A nasal passage NPconnects the nasal cavity NC to the pharyngeal wall PW. Below anepiglottis EP, the throat passage TP divides into a trachea TR forpassing air to the lungs and an esophagus ES for passing food and drinkto the stomach.

The soft palate SP is operated by muscles (not separately shown andlabeled) to lift the soft palate SP to urge the trailing edge TE againstthe rear area of the pharyngeal wall PW. This seals the nasal cavity NCfrom the oral cavity OC during swallowing. The epiglottis EP closes thetrachea TR during swallowing and drinking and opens for breathing.

For purposes of this disclosure, the nasal cavity NC, oral cavity OC andthroat passage TP are collectively referred to as the naso-pharyngealarea of the patient with the area including the various body surfaceswhich cooperate to define the nasal cavity NC, oral cavity OC and throatpassage TP. These body surfaces include outer surfaces of the nasalconcha C, the upper and lower surfaces of the soft palate SP and outersurfaces of the pharyngeal wall PW. Outer surfaces means surfacesexposed to air. Both the upper and lower surfaces of the soft palate SPare outer surfaces.

Snoring can result from vibration of any one of a number of surfaces orstructures of the naso-pharyngeal area. Most commonly, snoring isattributable to vibration of the soft palate SP. However, vibratoryaction of the nasal concha C and the pharyngeal wall PW can alsocontribute to snoring sounds. It is not uncommon for vibratory actionfrom more than one region of the naso-pharyngeal area to contribute tosnoring sounds. Sleep apnea can result from partial or full collapse ofthe naso-pharyngeal wall during sleep.

While most of the present discussion will describe placing a stiffeningimplant in the soft palate SP, it will be appreciated the presentinvention is applicable to other regions of the naso-pharyngeal areaincluding the nasal concha C and the pharyngeal wall PW.

The snoring sound is generated by impulses caused by rapid obstructionand opening of airways. Huang, et al., state the airway passage openingand closing occurs 50 times per second during a snore. Huang, et al.,utilize a spring-mass model (FIG. 5) to illustrate oscillation of thesoft palate in response to airflow (where the soft palate is the ball Bof mass depending by a spring S from a fixed anchor A).

Huang, et al., analogize the shortening of the soft palate SP inuvulopalatopharyngoplasty as effectively raising the critical air flowspeed at which soft palate flutter will occur. The shaded area SA inFIG. 3 shows the area of the trailing end TE of the soft palate SP to beremoved during this procedure. The alternative procedure proposed byHuang, et al., reduces the flexibility of the soft palate SP throughsurface scarring which is asserted as effecting the critical flow speed.The shaded area SA′ in FIG. 4 shows the area to be scarred by thisalternate procedure. In FIG. 4, dashed line L shows the demarcationbetween the soft and hard palates.

Using the spring-mass model of FIG. 5 as a convenient model of the softpalate SP, the present invention is directed to a surgical implant intothe soft palate SP to alter the elements of the model and thereby alterthe dynamic response of the soft palate SP to airflow. The implant canalter the mass of the model (the ball B of FIG. 5), the spring constantof the spring S, the dampening of the spring S or any combination ofthese elements. Unlike the prior art surgical techniques, the implantsthat will be described are easy to insert in a small incision resultingin reduced patient discomfort and are not exposed to the interior of themouth (such as the surface scarring of Huang, et al.) as a patientirritant. Also, as will be described, the degree of dynamic remodelingcan be fine tuned avoiding the need for excessive anatomicalmodification and are reversible in the event of adverse consequences.

B. Disclosure of Copending Applications

For purposes of illustrative background, FIGS. 6–15 and the related textbelow describe certain embodiments of inventions disclosed in theafore-mentioned U.S. patent application Ser. No. 09/513,432.

FIGS. 6–7 illustrate an embodiment where individual units 10 of mass (inthe form of implantable modular devices such as spheres or implants ofother geometry) are imbedded in the soft palate SP in close proximity tothe trailing end TE. With reference to the model of FIG. 5, the spheresadd mass to the mass-spring system thereby altering dynamic response toairflow and adding resistance to displacement and accelerating. Themodules are described as any bio-compatible material such as titanium orceramic.

The spheres may be sintered or otherwise provided with tissue growthinducing material on their outer surface. Such material permits andencourages tissue in-growth to secure the implant 10 in place. Also,placement of an implant 10 will induce a fibrotic response acting tostiffen the soft palate SP (and further alter the dynamic response andresistance to displacement and acceleration). A sintered or coatedsphere 10 will enhance the fibrotic response and resulting stiffening.

In addition to modifying the mass profile of the spring-mass system, thespring component S of FIG. 5 can be modified (alone or in combinationwith mass modification) to alter dynamic response. FIGS. 8–11 illustratean implant 20 in the form of a flexible strip for placement in the softpalate. The use of the term “strip” is not limited to long, narrowimplants but can also includes plates or other geometries implanted toalter the dynamic model of the soft palate SP.

The strip 20 has a transverse dimension less than a longitudinaldimension. By way of non-limiting example, the strip may have a lengthL_(S) of about 20–30 mm, a thickness T_(S) of about 2–4 mm and a widthW_(S) of 5–10 mm. As shown in FIG. 8, the strip 20 is embedded in thesoft palate SP with the longitudinal dimension L_(S) extending fromadjacent the hard palate HP toward the trailing end TE of the softpalate SP. As shown in FIG. 9, multiple strips 20 may be embedded in thesoft palate SP extending either straight rearward or angled to the sideswhile extending rearward.

Such stiffening of the soft palate SP stiffens and dampens the spring Sin the spring-mass system of FIG. 5 and alters the dynamic response ofthe soft palate SP. The strip 20 may be a spring having a springconstant to further resist deflection of the soft palate SP as well asurging the soft palate SP to the relaxed state of FIG. 5. The stiffnessof the strip 20, a spring constant of the strip 20, and the number ofstrips 20, are selected to avoid preclusion of closure of the softpalate SP during swallowing. Examples of suitable materials includetitanium and nitinol (a well-known nickel-titanium alloy). As with theexamples of FIGS. 9 and 10, the strips 20 may be provided with tissuein-growth surfaces or may be coated as desired.

FIG. 11 illustrates an implant 20′ formed of twisted or braided fibers103 a, 103 b. While a single type fiber could be used, the embodimentcan be formed of two different fibers 103 a, 103 b braided or twistedtogether. One fiber 103 a may be provided for encouraging fibroticresponse. Such a fiber 103 a may be polyester or silk suture material(in which individual fibers 103 a may be formed of braided or twistedelements). The other fiber 103 b may be a bio-resorbable fiber (e.g.,bio-resorbable suture material which may include natural materials suchas collagen or synthetic materials such as the PDS suture material).Alternatively, the second fiber 103 b may be a non-resorbable materialsuch as polypropylene suture material to provide added stiffness to theimplant. The fibers 103 a, 103 b may be bonded together along the axiallength of the implant 102′ to provide added stiffness.

FIGS. 12 and 13 show a delivery system 100 for placing an implant in thesoft palate SP. FIGS. 13–15 illustrate use of the novel delivery system100 with a strip implant 20 (such as implant 20′ of FIG. 11).

A needle 66 is provided having a ground beveled distal tip 61 forpiercing tissue of the soft palate. The needle 66 is hollow and carriesthe implant 20 in sliding close tolerance. A rod 64 is slidablypositioned in the needle 66 proximal to the implant 20. The implant 20is carried by the needle 66 to a desired implant site within the softpalate. At the desired site, the implant 20 is deployed by retractingthe needle 66 while holding the rod 64 in place. Relative movementbetween the rod 64 and needle 66 causes the rod 64 to dispel the implant20 from the needle 66 without need for moving the implant 20 relative tothe soft palate.

While advancing the needle 66 through the soft palate, tissue and bodyfluids may be inclined to enter the needle 66 and later interfere withdischarge of the implant 102 from the needle 66. An optional plug 104 isprovided to prevent admission of tissue into the needle 66. The plug 104is a bio-resorbable material. During discharge, the rod 64 (due toretraction of the needle 66) urges both the plug 104 and implant 20 outof the needle 66. Since the plug 104 is bio-resorbable, it resorbs intothe patient's body over time. The implant 20 provides the therapeuticeffect described above with reference to altering the dynamic responseof the soft palate.

To avoid the plug 104 being urged proximally into the needle 66, theneedle 66 includes a first bore 66 a having a diameter approximate tothat of the rod 64 and implant 20 and a second bore 66 b at the distaltip 61. The second bore 66 b is coaxial with the first bore 66 a and islarger than the first bore 66 a so that an annular retaining edge 65 isdefined within the needle 66. The plug 104 abuts the retaining edge 65and is restricted from being urged into the needle 66 as the needle 66is advanced through the tissue of the soft palate.

The needle 66 may be porous at the distal tip 61 so the needle with aloaded implant 20 may be soaked for sterilization if so desired.

C. Bolus of Particulate Matter

FIGS. 14 and 15 show an implant 20″ as a bolus of particulate matter. Anexample of such particulate matter would be micro-beads. An example ofsuch is taught in U.S. Pat. Nos. 5,792,478 and 5,421,406. These patentsteach carbon-coated metallic or ceramic particles having cross-sectionaldimensions of between 100 and 1,000 microns. The particles are carriedin a fluid or gel. These patents state that upon insertion into bodytissue, the particles do not migrate significantly and, apparently dueto fibrotic response, the tissue into which the particles are injectedstiffens.

The particles of U.S. Pat. Nos. 5,792,478 and 5,421,406 are one exampleof particles for stiffening injection. Such particles can also includeceramic particles or pure carbon or other bio-compatible particles. Forexample, the particles can be vitreous carbon, zirconia (ZrO₂), alumina(Al₂O₃) or polymeric. The particles can be carried in a liquid or gelmedium. The particles can have multi-modal particle size distributions(i.e., a mix of two or more sizes of particles with the smallerparticles filling interstitial spaces between larger particles).

The bolus 20″ of particles can be applied by a needle to inject thebolus 20″ into the soft palate SP. The bolus can be the same volume asthe volume of the implants 20 of FIGS. 8 and 9. With reference to FIG.15, a multiple of bolus injections can be made in the soft palateresulting in deposition of generally spherical deposits 20′″ ofparticles. Alternatively, an injecting needle can be withdrawn whilesimultaneously ejecting particles for the bolus 20″ (FIG. 14) to bedeposited in a line similar in dimensions to the implants 20 of FIGS. 8and 9.

The foregoing emphasizes the use of implants to stiffen the soft palateSP. Implants 20″ can be placed in any of the tissue of thenaso-pharyngeal area (e.g., the concha C or other nasal mucosal surface,soft palate SP or pharyngeal wall PW—lateral or posterior) to treatsnoring. Also, such a treatment can stiffen the tissue of the throat andtreat sleep apnea resulting from airway collapse by stiffening theairway.

While a needle deposition of a bolus of particles is presently mostpreferred, the bolus can be applied in other manners. FIG. 16illustrates deposition of particulates through a patch 200 having avolume 202 containing such micro-beads 204. One side 200 a of the patch200 contains an array of micro-needles 206 communicating with the volume202. The needles 206 may be small diameter, shallow penetration needlesto minimize pain and blood. Examples of shallow, small diameter needlesare shown in U.S. Pat. No. 5,582,184 to Erickson et al. Placing thesurface 200 a against the tissue (e.g., the pharyngeal wall PW as shownin FIG. 16), the needles 206 penetrate the outer surface of the tissuePW. The patch 200 can then be compressed (by finger pressure, roller orthe like) to eject the beads 204 from the volume 202 through theplurality of needles 206. The patch 200 can be provided with interiordividing walls (not shown) so that some of the volume of beads 204 isejected through each needle 206. In the figures, the thickness of thepatch 200 is exaggerated for ease of illustration.

Stiffening of the naso-pharyngeal tissue provided structure to reducevibration and snoring. Such structure reduces airway collapse as atreatment for sleep apnea.

The foregoing describes numerous embodiments of an invention for animplant for the naso-pharyngeal area to treat an upper airway condition.Having described the invention, alternatives and embodiments may occurto one of skill in the art. It is intended that such modifications andequivalents shall be included within the scope of the following claims.

1. A method for treating an upper airway condition of a patient, said method comprising: selecting an implant sized to be implanted into a tissue of a pharyngeal wall of said patient, said implant being formed of a material selected to induce a fibrotic response of material amount and having mechanical characteristics for said implant to passively, and without application of external energy, resist deflection of said wall and urge a deflected tissue to return to a rest state; and implanting said implant into said tissue of said pharyngeal wall.
 2. A method according to claim 1 wherein said implant is metal.
 3. A method according to claim 2 wherein said metal is nitinol.
 4. A method according to claim 1 wherein said implant has tissue in-growth areas.
 5. A method according to claim 1 wherein said condition is obstructive sleep apnea.
 6. A method according to claim 1 wherein said implant is not connected to a bony structure. 